It seems odd that any European tie at Celtic Park could ever be described as irrelevant. Current circumstances defy history. A crippling injury list and a manager facing a crucial Scottish Premier League match on Sunday rendered the Europa League visit of Rennes to Parkhead as something of an annoyance. Even, and he came close to admitting as much, to Neil Lennon himself.

Still, a 3-1 victory with a depleted team and recovery from a goal behind offered Lennon some Thursday night cheer. Crucially, Celtic's players performed as if their full weight is behind their manager.

Celtic will gladly glean some resource and morale boosts from the Europa League but they retain loftier aspirations. This season, their participation is only on account of Sion's expulsion. Onwards now to Motherwell, whose position as second to Rangers in the SPL provides an illustration of the current domestic heat on Lennon.

When Celtic look as flat as last weekend, and with Lennon having assembled the squad almost in its entirety now, the 40-year-old's ability to motivate is questioned. Now 12 points behind Rangers, Celtic and their former captain can barely afford further slip-ups; such a position can either inspire or scare teams.

Lennon knows better than anybody about the results-driven nature of Old Firm life. He alluded to that this week when contemplating this crucial spell for his own future. To his continual credit, the Northern Irishman is candid and forthright when discussing Celtic's troubles, added to how his own destiny is inextricably linked to them.

Mitigating circumstances, a severe batch of injuries most pertinently, count for nothing in this environment. Celtic boasted four of the SPL's best performers last term in Emilio Izaguirre, Beram Kayal, Gary Hooper and Kris Commons. A combination of injury and form loss has doused their contributions since July; must Lennon be responsible for that?

Anybody who speaks to Lennon as a matter of routine could only believe that he understands football and understands Celtic. Given his success as a player, he also comprehends fully what it takes to win SPL titles.

Last season, Celtic came within a point of doing that. Their football was generally impressive and had improved markedly from the disastrous Tony Mowbray era. Logic would say Lennon's young team would improve from that juncture; instead another sign of youthfulness – inconsistency – has appeared. The back-to-back meetings with Hibs highlight that much.

As has always been thus, the buck will stop at Lennon's door. It is easier, after all, to ship out a manager than a group of players. Still, when Celtic's board placed their faith in a young manager and mirrored that by continuing with the downsizing of the playing staff, surely some form of long-term plan was prevalent. Now, as Celtic are struggling and seeking experience, there are no players in the squad akin to Lennon or any of his team-mates during the halcyon Martin O'Neill era.

Some would object to that downsizing allegation, even although it is makes sense against a troubled commercial backdrop for Scottish football. When players of the calibre of Artur Boruc and Aiden McGeady departed Celtic, there was never the likelihood of equivalent talent being bought in.

The continuing frustration among the Celtic support, and it is an understandable one, is that the sensible off-field management of their club hasn't been replicated by trophy success. Salt is rubbed into that wound by Rangers' three championships in succession, claimed with financial turmoil for background.

In public, Lennon has always stressed he has the full backing of his board. Any other message would be a surprising one, and a criticism of his employers.

Lennon was on record as stating he wanted a powerful striker to supplement his squad with before this campaign started. It would also seem odd if the manager hadn't identified the need for meaningful fresh talent in defence. As no such players arrived, was Lennon let down by those above him?

Last season, Kelvin Wilson was signed from Nottingham Forest without Celtic coming up with sufficient money to prise the centre-back north before his contract expired. For all Celtic would argue the figure asked for was unrealistic, every player – and particularly those soon to become free transfers – has a price. Wilson, in turn, was frozen out for months in Nottingham; hardly a boost to his next club. Mohamed Bangura, the attacker signed before the end of the last transfer window, has shown nothing to suggest he was the kind of addition Lennon sought.

The position when Lennon accepted the Celtic job is the same as now: that top managers are hardly queueing for what was previously one of the more attractive posts in European football. That isn't, of course, a reason to stick with a coach who is failing but it offers tacit evidence of the size of Lennon's task.

The manager will pay the ultimate price if that challenge looks insurmountable. Nonetheless, it is a long way from logical that any replacement could oversee marked improvement.